This invention relates to a disc brake having first and second levers that respectively pivot on pins to transmit an axial clamping force that moves first and second friction members into engagement with a rotor to effect a brake application.
In disc brakes, it is common for a caliper to straddle a rotor that is fixed to an axle of a vehicle with the caliper is fixed to a yoke that is secured to the housing of the vehicle. The caliper has a bore therein that retains an actuation piston to define an actuation chamber. A first friction member is connected to the actuation piston while a second friction member is connected to an arm that extends from the caliper. The first and second friction members are located on opposite sides of the rotor and when pressurized fluid is supplied to the actuation chamber, the piston and caliper move in opposite directions such that the first and second friction members engage the rotor to effect a brake application. The following U.S. Patents may be considered as illustrative of such disc brake and their corresponding functional operation: U.S. Pat. Nos. 3,113,643; 3,421,604; 3,442,356; 3,868,001; 3,912,051; 3,998,466; 4,530,423; 5,660,253; 5,700,067; 5,713,435; 5,826,681; 5,845,747; 6,000,506; 6,044,936; 6,073,733; 6,135,245 and 6,454,056. While all of the disc brakes disclosed by these patents have certain differences they function in a manner as describe above wherein the friction members and the caliper slide on either pins or rails during a brake application. Unfortunately such sliding can often results in high friction forces that must be overcome before and during the movement of the friction members into engagement with a rotor to effect a brake application.
It is understood that elimination or a reduction of the friction forces would allow that portion of an actuation force to be directed to the development of a brake force and as a result the size of a caliper and weight of a brake may be reduced.